Restore former position of "Create New" menu item in viewport context menu

Summary:
I've seem various complaints from users about the fact that the Create New... menu
item in the viewport context menu is now below Open With item. All the other
changes to menus seem to have been well-received but this one has garnered criticism.
Looking through D23757 and D11884, I can't actually see that this was intentional, so
it might even be a bug.

Either way, this patch restores the old position of the Create New menu items at
the top of the Viewport context menu.

BUG: 417640
FIXED-IN: 20.04.0

Test Plan:

Reviewers: VDG, Dolphin, elvisangelaccio, ndavis

Reviewed By: VDG, ndavis

Subscribers: asturmlechner, markuss, kfm-devel

Tags: Dolphin

Differential Revision: https://phabricator.kde.org/D27267